Injection devices

ABSTRACT

A cap ( 16 ) is provided for the type of injection device ( 1 ) which presents a needle assembly ( 11 ) to the exterior thereof for removal after use. The cap is of two part construction with a shell ( 17 ) of hard material, having opposite inwardly flexible tongues ( 19 ) defined by slots in the shell, and an over-mould ( 18 ) of relatively soft deformable material, extending over at least the tongues and the slots. The tongues are squeezable towards each other through the over-mould to grip the needle assembly when the cap is fitted after an injection, thus enabling the needle assembly to be removed with the cap so that the user does not come into contact with the used needle.

BACKGROUND OF THE INVENTION

This invention concerns injection devices for medical use and inparticular caps for such devices.

DESCRIPTION OF THE RELATED ART

After use, the needle of a syringe has to be safely disposed of. In manyinjection devices the forward end of the syringe is left exposed so thatthe user can remove the needle assembly, leaving the capsule of thesyringe in place. It is not generally practical or recommended toreplace the plastic sheath which initially covers the needle. The tip ofthe needle can easily pierce the plastic. So the needle assembly has tobe unscrewed or pulled off with the needle tip exposed, and thisrepresents a danger.

However, most injection devices have a cap which fits to the forward endof the barrel that houses the syringe, this cap providing mechanicalprotection of the syringe housing. The cap is removed immediately priorto injection.

SUMMARY OF THE INVENTION

It is the aim of this invention to use the cap to remove the needleassembly safely after use.

According to the present invention there is provided a cap for aninjection device of the type which presents a needle assembly to theexterior thereof for removal after use, the cap being of two partconstruction with a shell of hard material having opposite inwardlyflexible tongues defined by slots in the shell and an over-mould ofrelatively soft deformable material extending over at least the tonguesand the slots, the tongues being squeezable towards each other throughthe over-mould to grip the needle assembly when the cap is fitted afteran injection.

With the needle assembly so gripped, the cap can be removed, for exampleby unscrewing, and the needle assembly will come with it. That assemblycan then be dropped into a sharps bin by relaxing the grip, and the userneed never touch it.

The cap will generally be elongate, closed at one end and open at theother. The tongues may be defined by generally U-shaped slots, the baseof each U being positioned away from the closed end of the cap.

The cap may be coned, narrowing towards its closed, forward end and thenthe arms of each U may converge towards each other so that the tongueswiden towards the open end, following the shape of the cap.

Preferably, the tongues will be thinner, over substantial part of theirarea, than the rest of the shell to facilitate flexure.

The over-mould need not conceal the whole shell, and it may be mainlyover just the tongues and slots, with its outer surface flush with theexposed parts of the shell.

Conveniently, the over-mould will be of rubber, with depressions formingfinger grips over the ends of the tongues which are to be pressedinwards. The over-mould may have a positive interlock with the shell,for example by inwardly projecting ribs engaging in slots in the shell.These may be adjacent the open end of the cap.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention one embodiment will now bedescribed, by way of example, with reference to the accompanyingdrawings, in which:

FIG. 1 is a cut-away perspective view of the leading end of an injectiondevice with a cap fully fitted,

FIG. 2 is a similar view of the device with the cap particularlywithdrawn and with a part thereof removed, and

FIG. 3 is another cut-away perspective view of the device from adifferent angle, with the cap particularly withdrawn and with a partthereof removed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The injection device 1 houses a syringe 2 of conventional form. It has acapsule 3 narrowing to a neck 4 at its leading end where it terminatesin a head 5 with a membrane 6 captive by a metal band 7. The syringe 2is entered into a two-part barrel comprising a main sleeve 8 containingmost of the capsule 3 and a leading part 9 which shrouds the forward endof the syringe. The part 9 reduces to an externally screwed threadedportion 10 closely embracing the head 5. This portion 10 receives aneedle assembly 11 comprising a cup-like element 12 which has arearwardly extending skirt 13 internally screw threaded to mate with theportion 10. A double-ended needle 14 extends co-axially through thethickened base of the cup, and when the needle assembly 11 is screwed onto the syringe carrier the rear end of the needle 14 punctures themembrane 6. Before an injection, the forward end of the needle 14 iscovered by a sheath 15.

This far, the arrangement is generally conventional.

Except when the device is actually being used the needle must beprotected by more than the sheath 15, and so the barrel has a cap 16which fits to its leading end. This is of a two-part constructioncomprising a hard plastics shell 17 and a rubber over-mould 18 shownonly in FIG. 1. The shell is of a cone-like form but is cut-away tocreate two diametrically opposed tongues 19 which join to the shell 17near the tip of the cone and which widen as they extend rearwardly.Externally the tongues step inwards at shoulders 20 near their narrowends so that they are mostly thinner than the rest of the shell. But attheir rear ends they have internal wedge-like formations 21 whichthicken towards the rear and which have axially parallel grooves 22. Thenature of the plastics material from which the shell 17 is moulded issuch that the tongues 19 can flex inwardly about their leading ends.

The rubber over-mould 18 extends over these tongues 19 and the slots bywhich they are defined. Externally, it is flush with the exposed partsof the shell 17 but in the region of the formations 21 the over-mouldhas shallow depressions 23 with studs 24. To the rear of these theover-mould thins and then terminates at inwardly projecting flanges 25which engage in diametrically opposed circumferential slots 26 in theshell 17.

After an injection the cap 16 is replaced on the barrel, but ultimatelythe needle assembly 11 has to be removed. Taking the cap off and thenunscrewing the assembly exposes the handler to being pricked by theneedle, which no longer has its sheath. But with this cap 16, bypressing the depressions 23 the tongues 19 flex inwardly and the wedgeportions 21 engage the skirt 13 of the needle assembly. The cap andbarrel are then mutually rotated and the gripped needle assembly isunscrewed. It can continue to be gripped by the cap as it is separatedfrom the barrel, and then dropped into a sharps bin by the handlerrelaxing his squeeze on the over-mould.

1. A cap for an injection device of the type which presents a needle assembly to the exterior thereof for removal after use, the cap being of two part construction with a shell of hard material having opposite inwardly flexible tongues defined by slots in the shell and an over-mould of relatively soft deformable material extending over at least the tongues and the slots, the tongues being squeezable towards each other through the over-mould to grip the needle assembly when the cap is fitted after an injection.
 2. A cap according to claim 1, which is of generally elongate form, closed at one end and open at the other.
 3. A cap according to claim 1, wherein the tongues are defined by generally U-shaped slots, the base of each U being positioned away from the closed end of the cap.
 4. A cap according to claim 1, which is coned, narrowing towards its closed, forward end.
 5. A cap according to claim 3, wherein the arms of each U converge towards each other so that the tongues widen towards the open end, following the shape of the cap.
 6. A cap according to claim 1, wherein the tongues are thinner, over a substantial part of their area, than the rest of the shell, to facilitate flexure.
 7. A cap according to claim 1, wherein the over-mould does not conceal the whole shell, and is mainly over just the tongues and slots, with its outer surface flush with the exposed parts of the shell.
 8. A cap according to claim 1, wherein the over-mould is of rubber, with depressions forming finger grips over the ends of the tongues which are to be pressed inwards.
 9. A cap according to claim 1, wherein the over-mould has a positive interlock with the shell.
 10. A cap according to claim 9, wherein the interlock is achieved by inwardly projecting ribs engaging in slots in the shell.
 11. A cap according to claim 10, wherein the ribs are adjacent the open end of the cap.
 12. A cap according to claim 2, wherein the tongues are defined by generally U-shaped slots, the base of each U being positioned away from the closed end of the cap.
 13. the cap of claim 1, wherein, the shell further comprises diametrically opposed circumferential slots perforating an entire thickness of the shell; and the over-mold further comprises inwardly projecting flanges engaged in the diametrically opposed circumferential slots in the shell.
 14. A cap for removing a used needle assembly from an injection device, comprising: a shell having slots and opposite inwardly flexible tongues defined by the slots, the shell including an interior end portion shaped to accept a syringe needle sheath; and a deformable outer skin moulded contactingly over at least the tongues and the slots of the shell, the tongues being squeezable towards each other through pressure exerted on the outer skin, the squeezed tongues gripping a syringe needle assembly to remove the needle assembly from an injection device.
 15. The cap of claim 14, wherein the outer skin is rubber and the shell is hard plastic.
 16. The cap of claim 14, wherein, the tongues are defined by generally U-shaped slots, the base of each U being positioned away from a closed end of the cap.
 17. The cap of claim 14, wherein, the shell further comprises diametrically opposed circumferential slots perforating an entire thickness of the shell; and the skin further comprises inwardly projecting flanges engaged in the diametrically opposed circumferential slots in the shell.
 18. A cap for removing a used needle assembly from an injection device, comprising: a hard shell having slots and opposite inwardly flexible tongues defined by the slots; and a deformable outer rubber skin fitted contacting at least the tongues and over the slots of the shell, the tongues being squeezable towards each other through pressure exerted on the outer skin, the squeezed tongues gripping a syringe needle assembly to remove the needle assembly from an injection device.
 19. The cap of claim 18, wherein, the tongues are defined by generally U-shaped slots, the base of each U being positioned away from a closed end of the cap. 